Heart disease is a significant health problem which has been the subject of substantial medical study. Bypass surgery has become commonplace; yet such surgery may be unavailable to many patients, either because of the nature of the occlusions or the physical condition of the patient.
One promising alternative technique for treating such cases is known as transmyocardial revascularization (TMR). Although this technique was considered as early as the work of Dr. C. Beck "the Development of a New Blood Supply to the Heart By Operation", Annals of Surgery, Vol. 102, No. 5 (11/35) pp. 801-813, the method was not extensively studied until the work of Dr. M. Mirhoseini and M. Cayton, an example of which is found in "Lasers in Cardiothoracic Surgery in Lasers in General Surgery (Williams and Williams; 1989) pp. 216-223.
Clinical tests have demonstrated that TMR channels, which generally communicate with the ventricle, facilitate revascularization of the heart muscle and recovery of heart function. Recent studies further demonstrate that beneficial revascularization also occurs following creation of channels that do not remain patent and channels that do not communicate with the ventricular chamber.
A laser device to perform TMR is described in Aita et al., U.S. Pat. No. 5,380,316, issued Jan. 10, 1995. In the procedure described in that patent, a number of channels are formed through the epicardium by means of a laser apparatus to extend through the myocardium to communicate with the ventricle. Other laser patents describing surgical transmyocardial revascularization include U.S. Pat. Nos. 5,554,152 and 4,658,817.
Unfortunately, laser techniques have some attendant difficulties. The laser equipment for performing such procedures is generally expensive, and, in some cases the lasers are large and cumbersome. Such lasers may be unavailable to smaller and more remote medical facilities. Some patients may therefore find it difficult to gain access to a properly equipped medical facility when treatment is needed. Additionally, lasing through the epicardium or endocardium, as described in many laser TMR procedures, may result in some destruction of viable vascular tissue contiguous to the epicardium or endocardium.
One alternative to the use of lasers would be to use a mechanical cutter to produce the channels. Early prior art methods of mechanical piercing and cutting of the heart wall were not pursued further because mechanical cutting did not produce patent channels.
A recent laser TMR device to perform transmyocardial revascularization includes some non-laser mechanisms and is described in PCT Patent Application Publication No. WO 96/35469. The PCT application briefly shows a mechanical auger, mechanical abrasion device, heat, a fluid jet, and a rotary toothed blade for mechanical TMR using a percutaneous approach. The mechanical devices described may produce an irregular cut in the myocardium which may result in leaving tissue flaps or fragments in the channel or ventricle. Such debris possibly could lead to life threatening emboli.
Commonly owned, co-pending U.S. patent application Ser. No. 08/713,531, filed on Sep. 13, 1996, describes mechanical TMR using cutting devices comprised of inner hollow needles or drill tipped devices mounted within outer hollow needles for transmyocardial revascularization. Additionally, a single rotating, hollow needle is described. A sharp cutting blade is used to produce a clean cut, although no specific mechanism is provided to positively ensure that tissue flaps do not remain. Commonly owned, copending U.S. patent application Ser. No. 08/773,778, filed on Dec. 26, 1996, also describes a mechanical cutting device used in conjunction with a laser to create drug delivery pockets and/or stimulation zones within myocardium. The laser is used to introduce the cutting device into the myocardium, and the cutting device defines two, hollow halves that snap together to cut tissue, which is trapped between the halves, to form pockets.
It would be desirable to produce clear, clean revascularization pathways that may be formed only in myocardium, if desired, while ensuring that excised tissue is cleanly removed without leaving tissue flaps and debris behind, using a relatively inexpensive and easily transportable mechanical heart surgical device suitable for heart biopsy and non-laser myocardial revascularization.